Field
The present invention relates generally to textured surfaces for display applications. For example, a textured surface as disclosed herein may be used in a light emitter (e.g., a backlight for certain display devices), the light emitter comprising a substrate with a textured surface on one or both major surfaces of the substrate that can operate as a light guide, and processes for making the light emitter. The light guide may include a pattern of discrete dots of material deposited thereon to control the light output of the light emitter. Textured surfaces disclosed herein may also be used as projections surfaces for viewing images from a projecting image source. In certain embodiments micro-replication (nano-replication) techniques may be used to efficiently and economically produce the textured surface. Textured surfaces disclosed herein may even be used to mitigate electrostatic charging for display glass substrates during certain manufacturing processes.
Technical Background
Conventional components used to produce diffused light have included diffusive structures, including polymer light guides and diffusive films which have been employed in a number of applications in the display industry. These applications include bezel-free television systems, liquid crystal displays (LCDs), electrophoretic displays (EPD), organic light emitting diode displays (OLEDs), plasma display panels (PDPs), micro-electromechanical structures (MEMS) displays, electronic reader (e-reader) devices, and others.
The desire for thinner, lighter and more energy efficient displays have led to the development of so-called transparent displays. Long a staple of science fiction, transparent displays are now being commercially implemented in several variations, including vending machine doors, freezer doors, retail advertising, augmented reality screens, heads-up displays in the automotive industry, smart windows for offices, portable consumer electronics, and security monitoring.
Unfortunately, transparent displays are susceptible to several poor performance characteristics. In actuality, currently available displays only partially transmit and reflect light, thus the contrast ratio of the display is greatly limited. Commercially available transparent displays typically offer only about 15% transmission, and performance is even lower in reflection mode.
For many practical applications, a transparent display requires the support of backplane illumination (via a transparent back light element). To maintain transparency, the back light needs to be fully transparent in an OFF-state and fully illuminated in an ON-state. Back lights having a frosted appearance are generally unacceptable. Additionally, the use of a transparent back light necessarily eliminates the use of a conventional reflective medium. Existing technology for providing backplane illumination are not satisfactorily meeting certain cost and performance requirements of the marketplace for transparent displays.
Other components of display devices, particularly the substrates forming the display panel itself, may present problems during manufacture of the thin film devices formed on at least one of the substrates. For example, triboelectrification can impede the ability to remove the substrate from surfaces in contact with the substrate, which can lead to breakage of the substrate and particle generation in some cases. This can be particularly troublesome for substrates, such as glass substrates, produced via processes that result in extremely smooth surfaces on the substrate.